Siemens RDG20 KN Series Basic Documentation page 52

Functions
4
Additional functions
Switching off external
equipment in Protection
mode
Energizing the contact
during heating/cooling
demand
Notes
Output heating/cooling
sequence
Humidity control
52 | 180
The relay output function can be enabled and tested as follows:
Relay output function
on ...
Q1
Q2
Q3
The external equipment (e.g., fan coil unit) can be switched off via relay output to
save energy when the thermostat is in Protection mode and no temperature control
is requested.
Set the related output parameter to 1 to enable the function.
Relay contact is open when the thermostat is in Protection mode.
NOTICE! The relay contact does not switch on when the room temperature is
below the frost protection setpoint.
For application examples, see Relay functions [➙ 163].
During heating or cooling demand, the relay contact can be energized to control
external equipment, e.g., to run the pump for a water system (fan coil unit) or a
compressor.
To reduce wear and tear on HVAC equipment, the minimum output On/Off time of
the Qx relay output can be adjusted (1...20 minutes) via P212 and P213. The
factory setting is 1 minute.
To enable the function, set the related output parameter:
●
To energize the output during heating/cooling demand, set the parameter to 2.
●
To energize the output during heating demand, set the parameter to 3.
●
To energize the output during cooling demand, set the parameter to 4.
For application examples, see Relay functions [➙ 163].
●
During heating demand, the relay contact remains Off only with electric heater
or radiator (output signal on Y2/Y20 > 0 V).
●
If the purge function (P251) is active (1...5 minutes every 2 hours), the relay
contact turns on to run the external equipment, e.g., a water pump.
This function switches the relay output on or off depending on the sequence, either
heating or cooling. The output can be used to release a heat pump compressor, a
reversing valve or 6-port ball valve as changeover.
To enable the function, set the related output parameter:
●
To close the contact when the thermostat is in heating mode (even in the dead
zone), set the parameter to 5.
●
To close the contact when the thermostat is in cooling mode (even in the dead
zone), set the parameter to 6.
For application examples, see Relay functions [➙ 163].
To reduce wear and tear on HVAC equipment, the minimum output On/Off time of
the Qx relay output can be adjusted (1...20 minutes) via P212 and P213. The
factory setting is 1 minute.
Depending on room humidity and the humidity setpoint, the humidity control
function switches the relay outputs to control the external equipment, e.g.,
dehumidifier/humidifier. See Humidity control [➙ 160].
To enable the function, set the related output parameter:
●
To control the dehumidifier, set the parameter to 7
●
To control the humidifier, set the parameter to 8
To reduce wear and tear on the HVAC equipment, the minimum output On/Off time
of the Qx relay output can be adjusted (1...20 minutes) via P212 and P213. The
factory setting is 1 minute.
Enable function via
Expert level parameter
P400
P401
P402
Test function via
diagnostic parameter
d08
d09
d10
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